1. Field of the Invention
This invention relates to self-loading material transporters, and more particularly, to self-loading material transporters having a tiltable conveyor system.
2. Description of the Prior Art
Numerous conveyor systems mounted on either a truck or a trailer and including a tiltable bed for loading and unloading materials are disclosed in various prior art references. U.S. Pat. No. 3,298,550 (Schiltz) discloses a haystack transporting device having a multiple chain conveyor system mounted on a tiltable bed. The multiple chain conveyor system is formed from six separate continuous conveyor chains. The ends of each conveyor chain are supported by sprocket wheels. A pair of drive chains are coupled at one end to a power take-off system which rotates at a velocity determined by engine RPM. The opposite end of each drive chain is coupled to independently rotatable drive axles each of which rotates a group of three conveyor chains. Each conveyor chain is provided with a plurality of outwardly extending, longitudinally spaced hook-like teeth which serve to engage the lower surface of the material being loaded or unloaded from the Schiltz conveyor system. Ten freely rotatable wheels are coupled to the lower, rear surface of the tiltable conveyor bed and serve to support the rear end of the conveyor bed when the conveyor bed is in the inclined loading/unloading configuration.
U.S. Pat. No. 4,096,960 (Gilmore) discloses a remotely controllable, trailer-mounted multiple chain conveyor system having a tiltable bed. U.S. Pat. No. 4,081,094 and Re. 30,404 (Pereira) discloses a conveyor trailer for transporting agricultural commodities. This device includes a multiple chain conveyor similar to the conveyor system disclosed in the Schiltz patent. The Pereira conveyor system also includes a plurality of flotation wheels mounted on the lower rear surface of the tiltable bed for maintaining a predetermined fixed spacing between the ground and the lower surface of the conveyor bed. A roller which is coupled to the lower surface of the tiltable bed engages a non-driven trailer wheel and rotates at a speed proportional to the trailer velocity. This trailer velocity input signal is utilized to synchronize the velocity of the multiple chain conveyor with the trailer velocity. The velocity measuring roller operates only when the tiltable conveyor bed has been fully displaced into the inclined loading position and must be maintained in firm, non-slipping contact with the trailer wheel in order to maintain proper synchronization of the multiple chain conveyor with the velocity of the supporting trailer.
U.S. Pat. No. 4,243,353 (Reed) discloses a multiple chain conveyor similar in contruction to that disclosed in the Schiltz patent. The conveyor disclosed by Reed also includes a separate speed metering wheel coupled to the lower rear surface of the tiltable conveyor bed. This speed metering wheel engages the ground only when the tiltable bed is fully inclined into the loading position and provided a proper ground speed indication only when the speed metering wheel is maintained in firm, non-slipping contact with the ground. A plurality of cleated drive wheels also extend from the lower surface of the tiltable conveyor bed and assist in propelling the conveyor system with respect to the ground.
U.S. Pat. No. 4,101,081 (Ritter) discloses a truck-mounted conveyor system having a tail section which can be dropped to the ground. Two parallel chain conveyor elements each include a plurality of load engaging tines and permit hay or similar materials to be loaded into the truck bed. The conveyor system is operated while the truck is maintained in a stationary position. The rear end of the conveyor system contacts the ground when the conveyor system is operated.
U.S. Pat. No. 3,317,066 (Hamm) discloses a trailer having vertical sidewalls and a non-tiltable conveyor belt which is located in the floor of the trailer bed. The Hamm conveyor system is intended to assist in loading or unloading materials from the trailer bed. As materials are loaded onto the trailer bed, a plurality of rectangular hinged panels are sequentially dropped into position. Each panel is closed over the upper surface of the conveyor belt as the trailer bed in front of that panel is loaded.
U.S. Pat. No. 3,927,780 (Dearlove) discloses a garbage collection vehicle which includes an inclined, non-tiltable conveyor system extending from the front portion of the vehicle. This conveyor system engages a trash bag, elevates the trash bag, and ejects it into an internally mounted garbage bin. The Dearlove conveyor system is operated when the vehicle is stopped.
U.S. Pat. No. 3,550,866 (Swenson) discloses a truck-mounted material spreader which utilizes a tine conveyor to discharge material from the truck bed at a rate proportional to the vehicle speed. A photoelectric sensor is utilized to measure vehicle speed. U.S. Pat. No. 3,929,292 discloses a material spreader which varies the rate of discharge of material from the spreader hopper at a rate proportional to the rate of movement of the vehicle.
U.S. Pat. No. 3,917,092 (McGinnis) discloses a nontiltable, flexible belt conveyor system which is coupled to a vehicle and serves to load, transport and unload material from the vehicle. The sides of the flexible conveyor belts are provided with a plurality of sprocket apertures.
U.S. Pat. Nos. 4,136,508 (Coleman), 4,229,931 (Schlueter), 4,227,363 (Kerber) and 3,728,851 (Van Antwerp) disclose a variety of ground engagement sensing devices each of which is coupled to the front portion of a powered agricultural vehicle to control the spacing between that portion of the vehicle and the ground.
The following U.S. Patents disclose a variety of vehicle-mounted conveyor systems having either tiltable or non-tiltable beds for loading or unloading material: Nos. 3,209,932 (Schiltz); 2,156,438 (Suverkrup); 2,526,960 (McElhinney et al.); 2,951,578 (Hibbard); 1,106,171 (Wangsness); 2,761,577 (Lahman); 2,418,726 (Rogers, Jr.); 1,258,351 (Martin); 1,628,871 (Bruce); 2,466,452 (Lisota); 3,025,982 (Quint); and 2,408,862 (Lisota).
As is readily apparant from a review of the Schiltz patents and related patents which disclose multiple chain conveyor systems, prior art systems of this type are mechanically highly complex in that a large number of chains which are fabricated from hundreds or thousands of separate mechanical elements are utilized. In addition, each chain is driven and supported by a pair of sprockets having large numbers of sprocket teeth which engage and rotate the conveyor chains. If a multiple chain conveyor system is not stopped after the material being loaded contacts the front end of the conveyor system, the load engaging teeth will continue to move and will rip tunnels in the non-moving bottom surface of the material. To reduce mechanical friction and wear of the various moving elements of the conveyor chains, the chains must be maintained in a well-lubricated state. This lubricant will be transferred from the chains to the lower surface of the material as it is loaded, transported or unloaded by the multiple chain conveyor systems discussed above. With certain materials such as cotton, this chain lubricant may stain the lower surface of the cotton unless appropriate precautions are taken.